1. Field of the Invention
The invention concerns a planar emitter with an emitter plane equipped with planar resonators and a network plane equipped with a coupling network whereby the planar resonators are coupled with one another in-phase and galvanically via the coupling network.
2. Description of Related Art
Reflector antennas or planar antennas or planar emitters are used for communications services, particularly multi-point, multi-channel communications services, that require reception or emission of directed electromagnetic emission fields of linear polarization in the microwave spectrum. The emitter characteristics of the reflector antennas are based on the production of an appropriate amplitude and phase relationship of the electromagnetic emission field components on the reflector surface by means of suitable exciters. The reflectors used in this case are either in the form of closed surfaces of defined curvature and envelope or are laid out using gridlike arrangements of discrete conductive linear elements of defined length and spacing. Conventional planar solutions are based on the arrangement of galvanically and parallel fed planar resonators of defined group size and spacing of each one.
A planar array-antenna in strip-conductor technology is described in ES 0 200 819. The mechanical construction consists of a first substrate plate as the carrier for antenna elements and a second substrate plate as carrier for the coupler and signal processing. Both substrate plates are connected to each other via a thick metal plate whereby the thickness of the metal plate corresponds to the half of the operational wave length. The electrical connection between the antenna elements on the front of the antenna and the couplers on the back of the antenna produce coaxial conductors that are insulated and are passed through the passages in the metal plate.
A planar antenna is described in ES 0 383 292 in which the antenna elements are glued to the earthing surface of a double-layered circuit board on which the coupling network and the additional electronics are situated. The antenna element consists of a planar resonator plate which is mounted on a dielectric substrate layer. The substrate layer of the antenna element is made of "glass epoxy" which, however, because of its dielectric characteristics has a negative influence on both efficiency and bandwidth.
A planar antenna is described in WO 95/09455 which is similarly constructed in a sandwich-like manner and in which, for production reasons, the layers carrying the antenna consist of two layers of the same material, since the antenna elements are capacitative coupled.
A disadvantage found in the conventional planar antennas is that they all provide for the most part high system quality only in a small spectral range and consequently are suitable only with limitations for use for multi-point multi-channel communications services, since only relatively few frequency bands using a single antenna are transmissible because of the small bandwidth. Due to their construction some of the antennas described are very heavy or are made of very expensive materials in order to reduce their weight.